The present invention generally relates to a golf ball, and more particularly, to a golf ball with improved dimples, in which a range of the total number of dimples which may be designed is broadened to provide the golf ball having the total number of dimples suitable for each user.
Conventionally, with respect to the arrangement of dimples to be provided on the surface of a golf ball, various techniques have been proposed for the purpose of mainly improving flight performance of the golf ball, and presently, the five following arrangements are chiefly put into actual application.
(1) Regular icosahedron arrangement (British Patent No. 1475413)
(2) Regular dodecahedron arrangement (U.S. Pat. No. 4,142,727)
(3) Icosahedron-dodecahedron arrangement (U.S. Pat. No. 4,560,168)
(4) Regular octahedron arrangement (U.S. Pat. No. 4,720,111)
(5) Concentric arrangement (Japanese Laid-open Patent Application Tokkaisho No. 53-115330)
Generally, in the arrangement of dimples for a golf ball, it is not preferable to adopt an arrangement with such a sharp directivity as will give rise to differences in trajectory due to a difference in a rotary axis of back spinning upon shooting the golf ball. Of the five arrangements referred to above, the regular icosahedron arrangement in item (1) and the concentric arrangement in item (5) are poor in the spherical symmetrical characteristic due to dimples arrangements thereof, with a consequently sharp directivity, and thus, can not be considered as preferable, without meeting the requirement for non-directivity.
Meanwhile, the total number of dimples to be provided on a golf ball is generally in the range of 300 to 600 pieces, and owing to the reason as described hereinafter, it is preferable to provide as many kinds of dimple total numbers for the designing as possible, within the above range and under the limitation effective from the viewpoint of the spherical symmetrical characteristic referred to earlier.
More specifically, as one of the aerodynamic effects of dimples, improvement of lift may raised. While flying as it is back spinning, a golf ball displaces a separating point of an air stream above the golf ball more rearwardly than that below said golf ball, and thus, pressure of air at the upper portion of the ball is reduced to a larger extent than that at the lower portion thereof, thereby to raise the ball higher, and such a lift may be increased by providing dimples on the surface of the golf ball in a proper number.
Within the range of the dimple total number of 300 to 600 pieces generally adopted for the golf ball as described above, the effect for the improvement of lift is increased with the decrease of the number of dimples so as to provide a golf ball for a high trajectory, while the effect for the lift improvement is reduced as the number of dimples is increased to provide a golf ball for a low trajectory as is known to those skilled in the art.
Accordingly, a golf player who will find it difficult to apply proper back spinning and to raise the golf ball high should preferably use a golf ball for the high trajectory with a small number of dimples, while on the contrary, a player who will lose a sufficient carry or be readily affected by wind, should desirably employ a golf ball for a low trajectory with many dimples.
In recent years when age, physical strength, ability, etc. of golf players are diversified due to increase of the golf playing population, it becomes desirable to provide dimple arrangements capable of designing the dimple total number in many kinds within the range of dimple total number of 300 to 600 pieces in order to prepare golf balls suitable for the respective golf players.
Upon review on the points as to whether or not the kinds of the dimple total number which can be designed are sufficiently many for the purpose, the dimple arrangements conventionally proposed as described earlier have various problems. More specifically, although the dodecahedron arrangement in item (2), icosahedron-dodecahedron arrangement in item (3) and regular octahedron arrangement in item (4) referred to earlier have no particular problems with respect to the symmetrical characteristic, there are such disadvantages that they are not sufficient in the freedom for the designing of the dimple total number, with the dimple total number which can be designed being undesirably limited, thus being unable to fully cope with the requirements in the field of this market as stated previously.